Time and Work Questions

FACTS  AND  FORMULAE  FOR  TIME  AND  WORK  QUESTIONS

 

 

1. If A can do a piece of work in n days, then A's 1 day's work =1n

2. If A’s 1 day's work =1n, then A can finish the work in n days.

 

3. A is thrice as good a workman as B, then:

Ratio of work done by A and B = 3 : 1.

Ratio of times taken by A and B to finish a work = 1 : 3.

 

NOTE : 

Efficiency1No of time units

 

 Efficiency × Time = Constant Work

 

Hence, Required time = WorkEfficiency

 

Whole work is always considered as 1, in terms of fraction and 100% , in terms of percentage.

In general, number of day's or hours = 100Efficiency

Q:

Adam and Smith are working on a project. Adam takes 6 hrs to type 36 pages on a computer, while Smith takes 5 hrs to type 40 pages. How much time will they take, working together on two different computers to type a project of 120 pages?

A) 8 hrs 45 min B) 8 hrs 42 min
C) 8 hrs D) 8 hrs 34 min
 
Answer & Explanation Answer: D) 8 hrs 34 min

Explanation:

Number of pages typed by Adam in 1 hour = 36/6 = 6
Number of pages typed by Smith in 1 hour = 40/5 = 8
Number of pages typed by both in 1 hour = (6 + 8) = 14
Time taken by both to type 110 pages = (120 * 1/14) = 847 = 8 hrs 34 min.

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10 4977
Q:

Two persons K and L can complete a piece of work in 30 days and 45 days respectively. If they work together, what part of the work will be completed in 3 days ?

A) 1/6 B) 1/3
C) 2/3 D) 1/18
 
Answer & Explanation Answer: A) 1/6

Explanation:

K's one day's work = 1/30
L's one day's work = 1/45
(K + L)'s one day's work = 1/30 + 1/45 = 1/18

The part of the work completed in 3 days = 3 (1/18) = 1/6.

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5 4958
Q:

28 Men and 52 women working together completes a work in 22.5 days. 35 men and 65 women working together on same work will complete it in how many days?

A) 16 B) 18
C) 19 D) 21
 
Answer & Explanation Answer: B) 18

Explanation:

Clearly total persons are increased in  28/35 :: 52/65 = 4:5.

As time is inversely proportional to men, so total time will decrease in the ratio 5:4.

Hence, 22.5 x 4/5 = 18 days.

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10 4938
Q:

P can do a piece of work in 5 less days than Q. If both of them can do the same work in 1119days, in how many days will Q alone do the same work  ?

A) 24 days B) 25 days
C) 20 days D) 19 days
 
Answer & Explanation Answer: B) 25 days

Explanation:

Let Q complete that work in 'L' days

 

=> 1L + 1L-5 = 9100

 

=> 9L2-245L+500=0

 

L = 25 days.

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11 4865
Q:

10 women can do a piece of work in 6 days, 6 men can do same work in 5 days and 8 children can do it in 10 days. What is the ratio of the efficiency of a woman, a man and a child respectively?

A) 4 : 6 : 3 B) 4 : 5 : 3
C) 2 : 4 : 3 D) 4 : 8 : 3
 
Answer & Explanation Answer: D) 4 : 8 : 3

Explanation:
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Q:

M, N and O can complete the work in 18, 36 and 54 days respectively. M started the work and worked for 8 days, then N and O joined him and they all worked together for some days. M left the job one day before completion of work. For how many days they all worked together?

A) 4 B) 5
C) 3 D) 6
 
Answer & Explanation Answer: B) 5

Explanation:

Let M, N and O worked together for x days.

From the given data,
M alone worked for 8 days
M,N,O worked for x days
N, O worked for 1 day

But given that
M alone can complete the work in 18 days
N alone can complete the work in 36 days
O alone can complete the work in 54 days

The total work can be the LCM of 18, 6, 54 = 108 units

M's 1 day work = 108/18 = 6 units
N's 1 day work = 108/36 = 3 units
O's 1 day work = 108/54 = 2 units

Now, the equation is
8 x 6 + 11x + 5 x 1 = 108
48 + 11x + 5 = 108
11x = 103 - 48
11x = 55
x = 5 days.

Hence, all M,N and O together worked for 5 days.

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3 4708
Q:

A mother can do a certain job in x hours. Her daughter takes twice as long to do the job. Working together, they can do the job in 6 hours. How many hours does the mother take to do the job ?

A) 3 B) 6
C) 9 D) 12
 
Answer & Explanation Answer: C) 9

Explanation:

The mother completes the job in x hours.
So, the daughter will take 2x hours to complete the same job.

 

In an hour, the mother will complete 1/x of the total job.
In an hour, the daughter will complete 1/2x of the total job.

 

So, if the mother and daughter work together, in an hour they will complete 1/x + 1/2x of the job.
i.e., in an hour they will complete 3/2x of the job.

 

The question states that they complete the entire task in 6 hours if they work together.
i.e., they complete 1/6 th of the task in an hour.

 

Equating the two information, we get 3/2x = 1/6
By solving for x, we get 2x = 18 or x = 9.

 

The mother takes 9 hours to complete the job.

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8 4614
Q:

Aadi can do a piece of work in 12 days alone, Bunny can do the same work in 16 days alone. After Aadi has been working for 5 days and Bunny for 7 days, Charan finishes it in 14 days. In how many days will Charan alone be able to do the work?

A) 96 days B) 48 days
C) 24 days D) 12 days
 
Answer & Explanation Answer: A) 96 days

Explanation:

Let number of days Charan can do the same work alone is 'd' days.

According to the given data,

512 + 716 + 14d = 114d = 1 - 20 + 214814d = 48 - 4148d = 14 x 487d = 96 days

 

Therefore, Charan alone can complete the work in 96 days.

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